Let u : [a, b] → R s be the solution of the well-posed first-order linear two-point boundary value problem Lu := u ′ + Qu = f a < x < b with homogeneous boundary conditions Au(a) − Bu(b) = 0, Thus u is a vector function from [a, b] to s-dimensional Euclidean space R s , and Q is an n × n matrix function. (A necessary but not sufficient condition for well-posedness is that the s × 2s partitioned...

We propose and study a posteriori error estimates for convection–diffusion–reaction problems with inhomogeneous and anisotropic diffusion approximated by weighted interiorpenalty discontinuous Galerkin methods. Our twofold objective is to derive estimates without undetermined constants and to analyze carefully the robustness of the estimates in singularly perturbed regimes due to dominant conve...

BACKGROUND Use of condoms in conjunction with other contraceptive methods has multiple benefits: prevention of unintended pregnancy, protection against sexually transmissible infections (STI), and sequentially, defence against the threat of infertility. However, few reviews compare dual method use prevalence or trends or systematically review the facilitators and barriers of dual method use acr...